The present invention relates to a system and method for providing real-time traffic data to vehicles traveling on roads, and more particularly, the present invention relates to a system and method that enables use of real-time traffic data with navigation data.
In some regional and metropolitan areas and countries, systems have been implemented that broadcast data messages that contain up-to-the-minute reports of traffic and road condition information. These systems broadcast these data messages on a continuous, periodic, or frequently occurring basis. These data messages are received by receivers installed in vehicles that travel in the region. The receivers decode the data messages and make the information in the messages available to the vehicle drivers.
These traffic data message broadcast systems have several advantages over the simple broadcasting of traffic reports over radio stations. For example, with these traffic data message broadcasting systems, a driver can obtain the traffic information quickly. The driver does not have to wait until a radio station broadcasts a traffic report. Another advantage of these traffic data message broadcast systems is that the driver does not have to listen to descriptions of traffic conditions for areas remote from his or her location. Another advantage of traffic data message broadcast systems is that more detailed and possibly more up-to-date information can be provided.
In these types of systems, the data messages conform to one or more pre-established specifications or formats. These specifications or formats are used by the on-board receivers in the vehicles that travel in the region to decode the traffic data messages.
One system for broadcasting real-time traffic and road condition information is the Radio Data System-Traffic Message Channel (xe2x80x9cRDS-TMCxe2x80x9d). The RDS-TMC system is used in some European countries. The RDS-TMC system is described in various publications, including xe2x80x9cRadio Data System, CENELEC END50067:1996, Specification of the Radio Data System.xe2x80x9d The RDS-TMC system broadcasts messages to vehicles using an FM station data channel. RDS-TMC messages are broadcast regularly or at varying intervals depending on the priority of the events being reported. Similar or identical systems are being used or are being planned in other countries and regions.
For purposes of identifying specific locations along roads to which the traffic messages pertain, location reference codes are assigned to locations along roads in a region. The locations to which location reference codes are assigned include intersections, interchanges, or other points along roads. Then, data messages are broadcast identifying traffic conditions relating to these locations. Thus, location reference codes are assigned only to these heavily traveled roads and not to lightly traveled roads. In some regions, location reference codes are assigned by a government institution. In other regions, location reference codes are assigned by a private enterprise.
Another, separate technology that has developed to assist drivers is the vehicle navigation system. Vehicle navigation systems provide various navigating features to drivers of vehicles, as well as others. The features provided by vehicle navigation systems differ from those provided by a traffic broadcast system. For example, a vehicle navigation system can calculate a specific route for a driver. The route calculated for the driver can begin at any street location in a covered geographic area and have a destination located at any other street location in the covered geographic region. The vehicle navigation system may also provide route guidance to the driver. The route guidance function can also be specific to the route calculated for the driver. The route guidance function may provide maneuvering instructions, audibly or visually, to the driver as the route is being followed. The vehicle navigation system may also provide other features, such as finding one or more destinations of a particular type within a given search area, such as all the Italian restaurants within two miles of a present position of the vehicle. In order to provide these kinds of functions, the vehicle navigation system uses a detailed geographic database, either located in the vehicle or accessible over a wireless communication link.
Both traffic data broadcast systems and vehicle navigation systems are useful to drivers. However, it would be even more useful if the data in the traffic data messages could be used with a vehicle navigation system. For example, it would be advantageous if the data in the traffic messages could be utilized when calculating a route using the route calculation function in a vehicle navigation system.
A method for providing this feature is disclosed in EP 1 004 852 A2, entitled xe2x80x9cMETHOD AND SYSTEM FOR USING REAL-TIME TRAFFIC BROADCASTS WITH NAVIGATION SYSTEMSxe2x80x9d, the entire disclosure of which is incorporated by reference herein. EP 1 004 852 A2 discloses a method and system in which location reference codes used in traffic messages are related to geographic data used by navigation systems thereby enabling navigation systems to use the information contained in traffic message broadcasts.
A further consideration to be addressed is that different location reference code systems exist in some regions. This may result from the introduction of different location reference code systems over time. As a result, the location reference codes used by some systems (such as vehicle navigation systems) may not match the location reference codes contained in the traffic messages broadcast by some traffic information providers, and vice versa. Accordingly, it would be beneficial to have a way to use traffic messages that contain location reference codes assigned by one entity in systems that support location reference codes assigned by another entity.
To address the above concerns, a system and method are disclosed that provide traffic information to end users. The traffic information is contained in traffic data messages that use location reference codes to identify locations along roads. A data structure is formed that relates a set of location reference codes assigned to locations along roads by a first data supplier to another set of location reference codes assigned to locations along roads by a second data supplier. The data structure is used to form traffic data messages containing location reference codes assigned by the first data supplier based on traffic data messages containing location reference codes assigned by the second data supplier.